I. Field of the Invention
The present invention relates to fluid filtering devices and, more particularly, to such a device adapted for connection to the suction line of a hydraulic pump.
II. Description of the Prior Art
Hydraulic fluid systems conventionally include a reservoir of hydraulic fluid, a suction line from the reservoir and to a hydraulic pump, and a return line from a hydraulic powered system to the reservoir. During operation of the hydraulic system a certain amount of contamination of the hydraulic fluid inherently occurs. These contaminates within the hydraulic fluid must be filtered from the fluid in order to prevent damage to the hydraulic system.
It has been the previous practice to connect fluid filtering devices on either the return line from the hydraulic system to the reservoir or, alternatively, to connect the fluid filtering device on the suction line from the reservoir into the hydraulic pump. Neither of these techniques, however, have heretofore proven entirely satisfactory in operation for the following reasons.
The connection of a filter device on the return line from the hydraulic system creates a back pressure to the hydraulic system as the filter element becomes clogged and thus disadvantageously reduces the overall efficiency of the hydraulic system. Conversely, connection of the fluid filtering device on the suction line can cause pump cavitation as the filter element clogs and such pump cavition can rapidly damage or even destroy the hydraulic pump. Consequently, the condition of the filter element must be carefully monitored when a fluid filtering device is connected to the suction line of the hydraulic pump.
A still further disadvantage of the previously known fluid filtering devices for hydraulic systems is that the fluid flow must be interrupted in order to replace or clean the filter element. The interruption of fluid flow, of course, results in down time for the hydraulic system and thus decreases the net work output from the system.
In still other types of hydraulic filtering devices, a filter assembly is insertable within a tubular and cylindrical housing having its lower end positioned within the fluid reservoir. The filter assembly further includes a tubular extension member having a cap formed at one end and a filter element secured to its other end. When the filter element becomes clogged, however, the entire filter assembly is removed, discarded and replaced by a new filter assembly. Disposal of the entire filter assembly, however, is unnecessarily expensive since, with the exception of the filter element itself, the remaining components of the filter assembly are reuseable.